Endohedral Clusterization of Ten Water Molecules into a “Molecular Ice” within the Hydrophobic Pocket of a Self-Assembled Cage

Yoshizawa, Michito; Kusukawa, Takahiro; Kawano, Masaki; Ohhara, Takashi; Tanaka, Ichiro; Kurihara, Kazuo; Nakabayashi, Nobuo; Fujita, Makoto

doi:10.1021/ja043953w

Cited by 281 publications

(149 citation statements)

References 23 publications

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“…The structure of water and the way it self-assembles and interacts with dissolved solutes and with hydrophobic surfaces continues to be highly topical [1][2][3][4][5]. Studies on water were ranked by Science as one of their top 10 breakthroughs of 2004 [6], and water structure in liquid as well as in the solid-state is the topic of more and more fundamental studies [7][8].…”

Section: Introductionmentioning

confidence: 99%

X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

Fucke

Steed

2010

Water

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A review. Diffraction methods are a powerful tool to investigate the crystal structure of organic compounds in general and their hydrates in particular. The laboratory standard technique of single crystal X-ray diffraction gives information about the molecular conformation, packing and hydrogen bonding in the crystal structure, while powder X-ray diffraction on bulk material can trace hydration/dehydration processes and phase transitions under non-ambient conditions. Neutron diffraction is a valuable complementary technique to X-ray diffraction and gives highly accurate hydrogen atom positions due to the interaction of the radiation with the atomic nuclei.Although not yet often applied to organic hydrates, neutron single crystal and neutron powder diffraction give precise structural data on hydrogen bonding networks which will help explain why hydrates form in the first place.

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Section: Introductionmentioning

confidence: 99%

X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

Fucke

Steed

2010

Water

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“…Central to these studies is the notion that the displacement of a high-energy water cluster from a receptor drives guest association, and in some cases, subsequent catalysis. However, despite the abundance of structural data documenting diverse water clusters encapsulated in various host cavities, mechanistic descriptions of the dynamic processes between water and host are rare (24)(25)(26)(27)(28)(29)(30)(31)(32).…”

mentioning

confidence: 99%

Protein-like proton exchange in a synthetic host cavity

Hart‐Cooper

Sgarlata

Perrin

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The mechanism of proton exchange in a metal-ligand enzyme active site mimic (compound 1) is described through amide hydrogendeuterium exchange kinetics. The type and ratio of cationic guest to host in solution affect the rate of isotope exchange, suggesting that the rate of exchange is driven by a host whose cavity is occupied by water. Rate constants for acid-, base-, and watermediated proton exchange vary by orders of magnitude depending on the guest, and differ by up to 200 million-fold relative to an alanine polypeptide. These results suggest that the unusual microenvironment of the cavity of 1 can dramatically alter the reactivity of associated water by magnitudes comparable to that of enzymes.W ater-mediated proton transfer in molecular cavities plays an essential role in the function of nature's remarkable metabolic machinery (1, 2). Of the broad diversity of enzymecatalyzed reactions, those involving transfer of hydrogen are ubiquitous and of high fundamental importance (3). For instance, ATP synthase employs an internal chain of water molecules to mediate proton transfer across an electrochemical gradient (4, 5). This process drives ATP synthesis, which allows organisms to broadly meet their basic energy needs. Recent studies of tunneling in enzymatic hydron transfer reactions have other far-reaching and broad implications, namely the importance of the dynamic enzyme motions in driving catalysis (6, 7).Of the methods used to study hydron transfer, kinetic studies of the mechanisms of amide hydrogen-deuterium exchange (HDX) have helped to elucidate the dynamic interactions between water and protein surfaces that are central to the unique capabilities of enzymes (8-13). Noncovalent interactions, such as electrostatic effects and hydrogen bonding, have also been shown to exert a significant influence on amide HDX rates. These properties are manifest in amide HDX rate constants that can vary by a factor of a billion for residues on the same protein (8). How these variations arise, and how such a property could be harnessed to drive enzyme-like reactivity, remain challenging questions.In a growing effort to emulate the efficacy of biological receptors and enzymes, studies of the preparative, guest-binding, and catalytic properties of synthetic assemblies have been pursued (14-21). Whereas guest encapsulation has been reported in a variety of media, association processes of organic guests are generally more thermodynamically favorable in water (22, 23). Central to these studies is the notion that the displacement of a high-energy water cluster from a receptor drives guest association, and in some cases, subsequent catalysis. However, despite the abundance of structural data documenting diverse water clusters encapsulated in various host cavities, mechanistic descriptions of the dynamic processes between water and host are rare (24-32).As part of the broader field of synthetic hosts previously mentioned, our group has developed a class of biologically inspired, anionic K 12 Ga 4 L 6 assemblies that exhibit cat...

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“…Such a structure for (H 2 O) 10 has not been described before in the literature, but a similar one has been predicted as one possible, but not the most stable, structure in ab initio studies. [28][29][30][31][32][33][34] Reaction O11 O10 Na2 Na1 Figure 1. The asymmetric unit of 1 (H atoms and non-coordinating solvent omitted for clarity).…”

Section: Resultsmentioning

confidence: 99%

From Simple Rings to One‐Dimensional Channels with Calix[8]arenes, Water Clusters, and Alkali Metal Ions.

Bergougnant¹,

Robin²,

Fromm³

2007

ChemInform

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Abstract-The macrocycle 4-tert-butylcalix [8]arene (L) was reacted with alkali metal carbonates (Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 , Rb 2 CO 3 , and Cs 2 CO 3 ) at the interface of a biphasic THF/water system. Needle-like crystals with a general formula [A x (4-tert-butylcalix[8]arenexH)(THF) y (H 2 O) z ] (with A¼Li, Na, K, Rb, Cs, x¼1, 2, y¼4, 5, 8, and z¼6, 7) were thereby obtained. The solid state structures were investigated by X-ray diffraction of single crystals and by TGA measurements. They do not appear to be maintained in solution.

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Endohedral Clusterization of Ten Water Molecules into a “Molecular Ice” within the Hydrophobic Pocket of a Self-Assembled Cage

Cited by 281 publications

References 23 publications

X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

Protein-like proton exchange in a synthetic host cavity

From Simple Rings to One‐Dimensional Channels with Calix[8]arenes, Water Clusters, and Alkali Metal Ions.

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